Aseismatic reinforcing structure of double flooring and aseismatic reinforcing method of double flooring

ABSTRACT

An aseismatic reinforcing structure of a double flooring and an aseismatic reinforcing method of the double flooring, in which by providing iron pillars for the double flooring in which a space is formed between a floor slab of a building and a floor portion supported to leg bodies arranged on the floor slab, a natural frequency of the floor portion is raised, and an amplification of a shake of a free-access panel constructing a floor surface that is caused by a resonance is prevented or suppressed, thereby improving aseismatic performance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an aseismatic reinforcing structure of a double flooring and an aseismatic reinforcing method of the double flooring.

2. Description of the Related Arts

In precision environment facilities such as a semiconductor manufacturing clean room in which a vertical diffusion furnace and the like are disposed, a double flooring structure in which a free-access floor is provided on a skeleton floor (floor slab) so as to have a predetermined height is often used.

In the double flooring structure, a method of improving aseismatic performance of the double flooring by reinforcing a fixing state of the free-access floor has been proposed (for example, see Japanese patent kokai No. 2001-107547 and Japanese patent kokai No. 10-299146).

It is, however, required to effectively improve the aseismatic performance of the double flooring.

SUMMARY OF THE INVENTION

The invention is made to solve the problem and it is an object of the invention to provide an aseismatic reinforcing structure of a double flooring and an aseismatic reinforcing method of the double flooring, in which the aseismatic performance of the double flooring can be effectively improved.

The aseismatic reinforcing structure of the double flooring of the invention has: leg bodies arranged on a floor slab of a building; a floor portion which is supported to the leg bodies and forms a space between the floor portion and the floor slab; and pillars which are provided for the floor slab of the aseismatic reinforcing region and are fixed to the aseismatic reinforcing region in the floor portion.

In an earthquake or the like, therefore, an amplification of a shake of the aseismatic reinforcing region in the floor portion due to a resonance of the aseismatic reinforcing region in the floor portion and the building is prevented or suppressed. That is, the aseismatic performance of the double flooring is effectively improved. Further, by providing the pillars only for the portion under the floor in the aseismatic reinforcing region where it is demanded to improve the aseismatic performance in the floor portion, the aseismatic reinforcement can be selectively performed.

In the aseismatic reinforcing structure of the double flooring of the invention, the pillars are joined to the floor slab and the floor portion by an adhesive agent.

A vibration that is caused when the pillars are joined to the floor slab and the floor portion is, therefore, prevented or suppressed.

In the aseismatic reinforcing structure of the double flooring of the invention, the floor portion has beams supported to the leg bodies and a floor panel which is fixed onto the beams and constructs a floor surface and the pillars are fixed to the beams.

Since the floor panel constructing the floor surface is fixed onto the beams, therefore, the floor panel can be easily attached/removed. For example, a reinforcing construction for providing the pillars under the floor is, consequently, easily performed. Even after the pillars were provided, the floor panel can be easily exchanged.

In the aseismatic reinforcing structure of the double flooring of the invention, the space is an under-floor space of the clean room where air is circulated.

A damage which is received by a vibration-disliking apparatus such as a semiconductor manufacturing apparatus which is disposed in the clean room at the time of an earthquake is, therefore, reduced.

According to the invention, there is provided an aseismatic reinforcing method of a double flooring in which a space is formed between a floor slab and a floor portion supported to leg bodies arranged on the floor slab of a building, wherein pillars are provided for the floor slab and the pillars are fixed to a floor portion in an aseismatic reinforcing region.

By providing the pillars for the existing double flooring, therefore, the resonance of the aseismatic reinforcing region in the floor portion and the building is prevented or suppressed, so that the aseismatic performance in the aseismatic reinforcing region of the double flooring is effectively improved.

By providing the pillars only for the portion under the floor in the aseismatic reinforcing region where it is demanded to improve the aseismatic performance in the floor portion, the aseismatic reinforcement can be selectively performed.

According to the aseismatic reinforcing method of the double flooring of the invention, the pillars are joined to the floor slab and the floor portion by the adhesive agent.

Since the vibration that is caused when the pillars are joined to the floor slab and the floor portion is, therefore, prevented or suppressed, for example, even in a state where the vibration-disliking apparatus which dislikes the vibration is disposed in the floor portion or even when the disposed apparatus is operating, the pillars are provided and the aseismatic reinforcement can be performed.

According to the aseismatic reinforcing method of the double flooring of the invention, the floor portion has the beams supported to the leg bodies and the floor panel which is fixed onto the beams and constructs the floor surface and the pillars are fixed to the beams.

Since the floor panel constructing the floor surface is fixed onto the beams, therefore, the floor panel can be easily attached/removed. For example, the reinforcing construction for providing the pillars under the floor is, consequently, easily performed. Even after the pillars were provided, the floor panel can be easily exchanged.

In the aseismatic reinforcing method of the double flooring of the invention, the space is an under-floor space of the clean room where the air is circulated.

The damage which is received by the vibration-disliking apparatus such as a semiconductor manufacturing apparatus which is disposed in the clean room at the time of an earthquake is, therefore, reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view with a part cut away illustrating a double flooring in an aseismatic reinforcing region to which an aseismatic reinforcing structure of a double flooring of the invention is applied;

FIG. 2 is a plan view of the double flooring to which the aseismatic structure of the invention is applied;

FIG. 3A is a side elevational view illustrating an iron pillar for aseismatic-reinforcing the double flooring;

FIG. 3B is a side elevational view when seen from a direction of F in FIG. 3A;

FIG. 4A is a cross sectional view taken along the line A-A in FIG. 3A;

FIG. 4B is a cross sectional view taken along the line B-B in FIG. 3A;

FIG. 5 is a graph showing a natural frequency when seen from a transfer function of a floor portion in the aseismatic reinforcing region;

FIG. 6 is a graph showing a natural frequency when seen from a transfer function of a floor portion out of the aseismatic reinforcing region;

FIG. 7A is a graph showing a response spectrum WY in the Y direction (south/north direction) obtained from a relation between a normalized acceleration in the Y direction of a first-floor portion of a building at the time of a past earthquake and the frequency;

FIG. 7B is a graph showing a response spectrum WX in the X direction (east/west direction) obtained from a relation between a normalized acceleration in the X direction and the frequency;

FIG. 8A is a graph showing a response acceleration of a building including a free-access panel in the aseismatic reinforcing region;

FIG. 8B is a graph showing a response displacement of the building including the free-access panel in the aseismatic reinforcing region;

FIG. 9A is a graph showing a response acceleration of a building including a free-access panel out of the aseismatic reinforcing region; and

FIG. 9B is a graph showing a response displacement of the building including the free-access panel out of the aseismatic reinforcing region.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view with a part cut away illustrating a double flooring in an aseismatic reinforcing region to which an aseismatic reinforcing structure of a double flooring of the invention is applied. FIG. 2 is a plan view of the double flooring to which the aseismatic structure of the invention is applied. FIG. 3A is a side elevational view illustrating an iron pillar serving as a pillar for aseismatic-reinforcing the double flooring. FIG. 3B is a side elevational view when seen from a direction of F in FIG. 3A. FIG. 4A is a cross sectional view taken along the line A-A in FIG. 3A. FIG. 4B is a cross sectional view taken along the line B-B in FIG. 3A (bolts are not shown). The aseismatic reinforcing structure of the double flooring of the invention is applied to a second-floor portion of a building.

As shown in FIGS. 1 and 2, a building 10 is manufacturing facilities of a semiconductor. The second-floor portion of the building 10 is a clean room where air purification is assured. The second-floor portion of the building 10 is a double flooring (free-access floor) 20 which has been aseismatic-reinforced by the aseismatic reinforcing structure of the invention. The double flooring 20 is constructed by: a floor portion 50 forming a space 40 between the floor portion 50 and a floor slab 30 (refer to FIG. 1) made of concrete and serving as a skeleton floor; and supporting legs 80 which are arranged on the floor slab 30 at a predetermined interval and support the floor portion 50.

The floor portion 50 is constructed by: boarding joists (beams) 70 and 72 provided in a lattice form over the floor slab 30 (refer to FIG. 1) along the Y direction (south/north direction) and the X direction (east/west direction); and free-access panels (floor panels) 60 which are fixed onto the boarding joists 70 and 72 and construct a floor surface of the second-floor portion. A distance between the floor slab 30 and each free-access panel 60 (refer to FIG. 1) is set to 1.5 m in the embodiment.

As illustrated in FIG. 1, each of the boarding joists 70 and 72 is made of steel or the like and has a cylindrical shape having an almost quadrangular cross sectional form. Each of the free-access panels 60 is fixed onto the boarding joists 70 and 72 by fixing members 62. In the embodiment, each of the free-access panels 60 has an almost square shape when seen as a plan view and two free-access panels 60 are arranged in a frame portion constructed by the boarding joist 70 and the boarding joist 72.

The boarding joists 70 and 72 are supported by the cylindrical supporting legs 80 arranged on the floor slab 30. In the embodiment, the supporting legs 80 are arranged at intervals of about 1.2 m (refer to L1 in FIG. 2). In the embodiment, each of the supporting legs 80 is set into a size of φ −89.1

2.3.

A lower portion of each of the supporting legs 80 is fixed by a fixing plate 84 formed with a vertical rib 82. The fixing plate 84 is fixed onto the floor slab 30 by anchor bolts 86. An upper portion of each of the supporting legs 80 is coupled with an attaching metal fitting 88 fixed to a side wall of the boarding joist 70 with bolts.

As mentioned above, the second-floor portion of the building 10 is the double flooring 20 in which the boarding joists 70 and 72 are supported by each of the supporting legs 80 arranged on the floor slab 30 and the free-access panels 60 are fixed onto the boarding joists 70 and 72 by the fixing members 62.

Air holes 64 are formed in each of the free-access panels 60 so that air can be circulated between the portion under the floor and the portion above the floor. Although only a part of the air holes 64 are illustrated in FIG. 1 in order to avoid complexity of the diagram, the air holes 64 are actually formed in the whole surface of each of all of the free-access panels 60 at regular intervals.

A vertical diffusion furnace (not shown) as a vibration-disliking apparatus is disposed on the free-access panels 60 of the double flooring 20 in the second-floor portion of the building 10. The region where the vertical diffusion furnace apparatus is disposed is a region shown by an alternate long and short dash line R in FIG. 2 and the region is set to an aseismatic reinforcing region R where the aseismatic reinforcement is performed.

Subsequently, the aseismatic reinforcement in the aseismatic reinforcing region R will be described.

As shown in FIG. 1, iron pillars 100 serving as pillars are attached below the free-access panels 60 in the aseismatic reinforcing region R (refer to FIG. 2). The iron pillars 100 are joined to the floor slab 30 and the boarding joists 70 and 72 (refer to FIG. 2). In the embodiment, the iron pillars 100 are arranged under the boarding joists 70 and 72 at intervals of about 2.4 m (refer to L2 in FIG. 2).

As shown in FIGS. 1, 3A, 3B, 4A, and 4B, each of the iron pillars 100 has a pillar body 102 having an almost H-shaped horizontal sectional form. An upper plate 104 is provided in an upper portion of the pillar body 102 (FIG. 4A) and a lower plate 106 (FIG. 4B) is provided in a lower portion (the pillar body 102, upper plate 104, and lower plate 106 are integrated). In the embodiment, the pillar body 102 of the iron pillar 100 is set to a size of H −396

199

7

11.

As shown in FIGS. 1, 3A and 3B, the lower plate 106 of the iron pillar 100 is fixed to the floor slab 30 with anchor bolts 120. A space between the lower plate 106 and the floor slab 30 is filled with an epoxy resin 112 (in other words, the epoxy resin (layer) 112 is sandwiched between the lower plate 106 and the floor slab 30).

The upper plate 104 of the iron pillar 100 is fixed to an L-shaped attaching metal fittings 130 joined to the side surfaces of the boarding joists 70 and 72 with bolts 122. As shown in FIG. 3B, spaces between the side surfaces of the boarding joists 70 and 72 and the attaching metal fittings 130 are filled with epoxy resin 114 (in other words, the epoxy resin (layers) 114 is sandwiched between each of the side surfaces of the boarding joists 70 and 72 and the attaching metal fittings 130).

Since the upper plate 104 and the lower plate 106 are fixed with the bolts, the iron pillar 100 can be attached/removed.

The joint (fixing) of the iron pillar 100 and the floor slab 30 and the boarding joists 70 and 72 may be made by an arbitrary joining method. For example, they may be joined (fixed) with an adhesive agent made of an epoxy resin or the like.

Subsequently, the operation and effects of the embodiment will be described.

FIGS. 5 and 6 show natural frequencies based on a transfer function of the floor portion 50. FIG. 5 shows the natural frequency of the aseismatic reinforcing region R in the floor portion 50 (refer to FIG. 2) which has been aseismatic-reinforced by the iron pillars 100 (refer to FIGS. 1, 3A and 3B). FIG. 6 shows the natural frequency of a region K out of an aseismatic reinforcing region in the floor portion 50 which is not aseismatic-reinforced.

As will be understood from FIGS. 5 and 6, while the natural frequency of the region K out of the aseismatic reinforcing region in the floor portion 50 is equal to about 3.8 Hz, the natural frequency of the aseismatic reinforcing region R in the floor portion 50 is equal to 23.3 Hz.

Graphs of FIGS. 7A and 7B show response spectra obtained from a relation between a normalized acceleration and a frequency of the first-floor portion of the building 10 at the time of the past earthquake. FIG. 7A is the graph showing a response spectrum WY in the Y direction (south/north direction) and FIG. 7B is the graph showing a response spectrum WX in the X direction (east/west direction).

As mentioned above, each of the response spectra WY and WX of the building 10 has a peak in a range from 3 Hz to 10 Hz. The value 23.3 Hz (refer to FIG. 5) as a natural frequency of the aseismatic reinforcing region R (refer to FIG. 2) is, therefore, fairly higher than the natural frequency (3 Hz to 10 Hz) of the building 10. The value 3.8 Hz (refer to FIG. 6) as a natural frequency of the region K out of the aseismatic reinforcing region which is not aseismatic-reinforced (refer to FIG. 2), however, coincides with the natural frequency (3 Hz to 10 Hz) of the building 10.

FIGS. 8A and 9A are graphs showing (presumed) response accelerations of the building 10. FIGS. 8B and 9B are graphs showing (presumed) response displacements of the building 10. In both of the graphs, an ordinate axis indicates a height from the ground of the building 10. Values at the height of about 5.8 m indicate the response acceleration and the response displacement of the floor slab 30 in the second-floor portion (refer to FIGS. 1, 3A and 3B). Portions surrounded by an alternate long and short dash line in each diagram indicate the response acceleration and the response displacement of the free-access panel 60 disposed at the position that is 1.5 m above the floor slab 30.

FIGS. 8A and 8B show the response acceleration and the response displacement of a free-access panel 60 in the aseismatic reinforcing region R (refer to FIG. 2) to which the invention is applied, that is, which has been aseismatic-reinforced by the iron pillars 100 (refer to FIGS. 1, 3A and 3B). FIGS. 9A and 9B show the response acceleration and the response displacement of a free-access panel 60 in the region K out of the aseismatic reinforcing region (refer to FIG. 2) to which the invention is not applied, that is, which is not aseismatic-reinforced by the iron pillars 100 (refer to FIGS. 1, 3A and 3B).

As will be understood by comparing FIGS. 8A and 8B with FIGS. 9A and 9B, in the case of the free-access panel 60 in the region K out of the aseismatic reinforcing region which is not aseismatic-reinforced by the iron pillars 100 (refer to FIGS. 1, 3A and 3B), since the natural frequency is close to the natural frequency of the building 10, the panel resonates and the shake is amplified. Specifically speaking, the shake of the free-access panel 60 in the region K out of the aseismatic reinforcing region (refer to FIG. 2) is amplified to 470 gal in the X direction and 497 gal in the Y direction as a maximum acceleration and to 0.82 cm in the X direction and 0.83 cm in the Y direction as a maximum displacement.

In the case of the free-access panel 60 in the aseismatic reinforcing region R which has been aseismatic-reinforced by the iron pillars 100 (refer to FIGS. 1, 3A and 3B), since the natural frequency is fairly higher than the natural frequency of the building 10, the amplification of the shake of the free-access panel 60 due to the resonance is prevented or suppressed. The shake of the free-access panel 60 in the aseismatic reinforcing region R (refer to FIGS. 2, 3A and 3B) is suppressed to 232 gal in the X direction and 280 gal in the Y direction as a maximum acceleration and to 0.23 cm in the X direction and 0.17 cm in the Y direction as a maximum displacement. That is, by performing the aseismatic reinforcement to which the invention is applied, the response acceleration is reduced by 40% or more and the response displacement is reduced to about ⅓. In other words, the aseismatic performance of the double flooring 20 in the aseismatic reinforcing region R (refer to FIGS. 3A and 3B) is effectively improved.

By raising rigidity of the floor portion 50 by providing the iron pillars 100 for the double flooring 20 as mentioned above, more specifically speaking, by raising rigidity of the boarding joists 70 and 72 which fix the free-access panel 60 constructing the floor surface, the natural frequency is raised, the amplification of the shake of the free-access panel 60 constructing the floor surface is prevented or suppressed, and the aseismatic performance is improved.

As shown in FIGS. 7A and 7B, since there is such a tendency that the response spectrum (response value) of the building 10 decreases when the natural frequency exceeds 10 Hz, by setting the natural frequency of the free-access panel 60 (floor portion 50) to a frequency higher than 10 Hz as in the embodiment, the amplification of the shake due to the resonance of the free-access panel 60 (floor portion 50) and the building 10 is effectively prevented or suppressed, so that the aseismatic performance can be effectively improved.

Although the natural frequency of the free-access panel 60 (floor portion 50) is set to 23.3 Hz in the embodiment, the invention is not limited to the special frequency. It is sufficient that in accordance with the natural frequency of the building, the natural frequency of the floor portion 50 is set to a natural frequency adapted to effectively prevent or suppress the resonance with the building.

As described above, in order to prevent or suppress the resonance of the building 10 and the free-access panel 60 (floor portion 50), it is sufficient that a frequency region of the natural frequency of the building 10 and the natural oscillation of the free-access panel 60 (floor portion 50) can be shifted.

For this purpose, a method whereby the double flooring 20 is abandoned and a steel frame floor or a concrete floor having high rigidity is used is also considered. To perform those measures, however, it is necessary to temporarily move the vertical diffusion furnace apparatus (not shown) disposed in the aseismatic reinforcing region R and stop the producing operation for a long period of time. In many cases, the space between the free-access panel 60 and the floor slab 30 (portion under the floor) is a utility space and pipes, ducts, power cables, and the like are arranged in all directions, it is, therefore, very difficult to arrange the large steel frame floor or concrete floor. Even in a situation where they can be disposed, there are many problems such as influence of a clean room environment contamination due to pouring of concrete or the like and expensive construction costs.

According to the embodiment, after the vertical diffusion furnace apparatus (not shown) was disposed in the aseismatic reinforcing region R (refer to FIG. 2) of the free-access panel 60 of the existing double flooring 20, the iron pillars 100 are provided only for the apparatus lower portion (aseismatic reinforcing region R) and the aseismatic reinforcement is selectively performed, thereby improving the aseismatic performance. The operation of the vertical diffusion furnace apparatus, therefore, is not ceased or, even if it is ceased, its ceasing period of time is short. An enough large space adapted to pass wirings, gas pipes, and the like can be assured in the space under the floor of the apparatus lower portion.

As for the joint (fixing) of the iron pillars 100 and the floor slab 30 and the boarding joists 70 and 72, by joining (fixing) them with an adhesive agent made of the epoxy resin or the like, the vibration that is caused upon joining is prevented or suppressed. In the case of performing the aseismatic reinforcement during the producing operation of the vertical diffusion furnace, therefore, it is desirable to join the iron pillars 100 and the floor slab 30 and the boarding joists 70 and 72 by the adhesive agent.

By fixing the iron pillars 100 with the bolts as in the embodiment, the iron pillars 100 can be easily attached/removed. Even in the case where the vertical diffusion furnace apparatus is, therefore, moved to another region in association with a layout change or the like, by removing and moving the iron pillars 100, the layout change can be easily realized. The iron pillars 100 may be fixed by a method other than the bolt fixing method so that they can be easily attached/removed.

Since the free-access panel 60 constructing the floor surface is merely fixed onto the boarding joists 70 and 72 by the fixing members 62, they can be easily attached/removed. For example, therefore, the free-access panel 60 can be removed and arranged to the portion under the floor (space between the free-access panel 60 and the floor slab 30) or the free-access panel 60 can be easily exchanged.

The invention is not limited to the embodiment. For example, although the aseismatic reinforcement is performed to the existing double flooring 20 after that in the embodiment, the invention is not limited to it. The aseismatic reinforcement may be performed at the time of new construction or construction of the double flooring.

For example, although the aseismatic reinforcement has been performed to the partial aseismatic reinforcing region of the double flooring 20 in the embodiment, the invention is not limited to it. The aseismatic reinforcement may be performed to a plurality of aseismatic reinforcing regions of the double flooring 20 or the aseismatic reinforcement may be performed to the whole region of the double flooring 20.

Although the embodiment relates to the structure in which the free-access panel 60 constructing the floor surface is fixed onto the boarding joists 70 and 72 supported to the supporting legs 80, the invention is not limited to the special structure. A structure in which portions having high rigidity such as outer frame portion or corner portions of the free-access panel are directly supported by the supporting legs without providing the boarding joists 70 and 72 may be used, or a construction in which the free-access panel and the supporting legs are integrated may be used. In the case, the pillars are joined to the portions having the high rigidity of the free-access panel.

This application is based on a Japanese Application No, 2008-184709 which is hereby incorporated by reference. 

1. An aseismatic reinforcing structure of a double flooring, comprising: leg bodies arranged on a floor slab of a building; a floor portion which is supported to said leg bodies to form a space between said floor portion and said floor slab; and pillars which are provided for said floor slab and fixed to an aseismatic reinforcing region in said floor portion.
 2. The structure according to claim 1, wherein said pillars are joined to said floor slab and said floor portion by an adhesive agent.
 3. The structure according to claim 2, wherein said floor portion has beams supported to said leg bodies and a floor panel which is fixed onto said beams to construct a floor surface, and said pillars are fixed to said beams.
 4. The structure according to claim 1, wherein said space is a space under a floor of a clean room in which air is circulated.
 5. The structure according to claim 3, wherein said beams are provided in a lattice form over said floor slab.
 6. The structure according to claim 1, wherein said aseismatic reinforcing region is a region where a vertical diffusion furnace apparatus is disposed in said floor portion.
 7. An aseismatic reinforcing method of a double flooring in which a space is formed between a floor slab of a building and a floor portion which is supported to leg bodies arranged on said floor slab, comprising the steps of: providing pillars for said floor slab; and fixing said pillars to an aseismatic reinforcing region in said floor portion.
 8. The method according to claim 7, wherein said pillars are joined to said floor slab and said floor portion by an adhesive agent.
 9. The method according to claim 8, wherein said floor portion has beams supported to said leg bodies and a floor panel which is fixed onto said beams and constructs a floor surface, and said pillars are fixed to said beams.
 10. The method according to claim 7, wherein said space is a space under a floor of a clean room in which air is circulated.
 11. The method according to claim 9, wherein said beams are provided in a lattice form over said floor slab.
 12. The method according to claim 7, wherein said aseismatic reinforcing region is a region where a vertical diffusion furnace apparatus is disposed in said floor portion. 